JPH04364649A - Video signal transmitter utilizing telephone line - Google Patents

Abstract

PURPOSE: To transmit massive information at high speed by converting the data of video signals into sine wave signals at a prescribed frequency, transmitting them to a telephone line, detecting the zero point of received signals, counting its frequency and converting them to the video signals. CONSTITUTION: Video signals outputted from a camera 1 are converted into digital signals and stored in a memory 3. The data in the memory 3 are read out by a CPU 6, converted into since wave signals at the prescribed frequency, corresponding to the data by a data/frequency converter 7 and transmitted through an interface circuit 12 to a telephone line 20. For the sine wave signals received by the circuit 12, on the other hand, zero point is detected by a zero- point detector 14, and the frequency is counted by a counter 15 based on a detecting signal and the oscillate signal of an oscillator 16. Then, these signals are converted into digital data by a frequency/data converter 17, further, converted into video signals by a converter 18, and displayed on a monitor 19. Thus, massive information can be transmitted at high speed within a narrow band.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a video signal transmission device using a general telephone line, and more specifically, to a video signal transmission device that uses a general telephone line to process various video data information at high speed. The present invention relates to a video signal transmission device.

0002

2. Description of the Related Art Conventionally, in a video signal transmission device, as shown in FIG. The signals are synchronized and converted into digital signals, and the digitally converted signals are recorded in the memory 32 under the control of the memory controller 42 which is controlled by the central processing unit 40. The signal is read in accordance with the control and modulated by a modulator 33 , and the modulated signal is amplified by an amplifier 34 and then transmitted through a telephone line 43 through a telephone line interface circuit 35 .
After amplifying the signal received by the receiver amplifier 36, the demodulator 37 demodulates it to the original signal under the control of the central processing unit 40, and the demodulated signal is sent to the digital/analog converter 3.
8 to convert it into an analog signal and display it on the monitor 39. And, when modulating the modulator 33,
An amplitude modulation method or a phase modulation method has been used, or an amplitude phase modulation method that is a combination of amplitude modulation and phase modulation has been used.

0003

[Problem to be Solved by the Invention] However, in such conventional video signal transmission devices, although the amount of information in the video signal is large, the capacity of the transmission line is insufficient, so that the amount of information transmitted through the transmission line is insufficient. When transmitting information, there is a disadvantage that it takes a considerable amount of time to transmit the information. In order to solve these problems, the inventors of the present invention have conducted extensive research and have attempted to provide the following video signal transmission device using a general telephone line.

0004

SUMMARY OF THE INVENTION An object of the present invention is to provide a video signal transmission device using a general telephone line that can transmit a large amount of video data at high speed. The purpose of the present invention is to convert the video signal output from the camera into digital data, store it in a memory under the control of the central processing unit, read the stored data under the control of the central processing unit, and convert the data into digital data. After converting the signal into a frequency, it is transmitted to the telephone line through the telephone line interface circuit, and after amplifying the signal received through the telephone line and into the telephone line interface circuit, it becomes zero (Zero).
) point, count the frequency using the zero point detection signal, convert it to data, convert the data to an analog signal, and configure a video signal transmission device using a general telephone line so that it can be displayed on a monitor. This is achieved by

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. As shown in FIG. 1, there is a timing generator 4 that generates a timing signal, and an A/D converter 2 that synchronizes the video signal output from the camera 1 with the timing signal of the timing generator 4 and converts it into a digital signal. , a central processing unit 6 which receives the timing signal from the timing generator 4 and controls the operation of the entire system; and a memory control unit 5 which receives the timing signal from the timing generator 4 and is controlled by the central processing unit 6. , a memory 3 which stores the output signal of the A/D converter 2 under the control of the memory control unit 5 and then reads and outputs it under the control of the central processing unit 6; and an oscillator 9 which generates a predetermined oscillation signal. , a prescaler 8 that frequency-divides the oscillation signal of the oscillator 9, and a data/data converter that converts the output data of the memory 3 into a frequency using the frequency-divided signal of the prescaler 8.
a frequency converter 7; an amplifier 10 for amplifying the output signal of the data/frequency converter 7 and transmitting it to the telephone line interface circuit 12; and a receiving amplifier for amplifying the received signal received through the telephone line interface circuit 12. 13, a zero point detector 14 that detects the zero point of the output signal of the receiving amplifier 13 and outputs it as a rectangular wave signal, an oscillator 16 that generates a predetermined oscillation signal, and the zero check using the oscillation signal of the oscillator 16. A frequency counter 15 that counts the output signal frequency of the frequency counter 14, a frequency/data converter 17 that converts the output signal of the frequency counter 15 into original digital data, and a frequency/data converter 17 that converts the output signal of the frequency/data converter 17 into original digital data. D/A converts to analog signal and displays on monitor 19
The converter 18 and the buffer 11 which applies the output of the memory 3 to the monitor 19 under the control of the central processing unit 6 constitute a video signal transmission device using a telephone line according to the present invention. In the figure, an unexplained reference numeral 20 indicates a telephone line. Further, as shown in FIG. 2, the data/frequency converter 7 includes a programmable frequency divider 50 that converts the output data of the memory 3 into a rectangular wave of a predetermined frequency using the frequency division signal of the prescaler 8; A rectangular wave/sine wave converter 51 converts the output signal of the programmable frequency divider 50 into a sine wave.

The operation of the video signal transmission apparatus using a telephone line according to the present invention constructed as described above will be explained as follows using FIGS. 3 to 5. The video signal output from the camera 1 is synchronized with the timing signal of the timing generator 4 by the A/D converter 2 and converted into a digital signal. stored in Next, the digital data of the video signal stored in the memory 3 is read from the memory 3 under the control of the central processing unit 6, and then the data/frequency converter 7 generates a frequency corresponding to the data of the video signal. That is, at this time, the oscillation signal output from the oscillator 9 is frequency-divided in advance by the prescaler 8 and then applied to the data/frequency divider converter 7 to generate a frequency corresponding to the data of the video signal. This operation is shown in Figure 2.
To explain in detail, the high frequency generated by the oscillator 9 is divided in advance by the prescaler 8, and the divided signal is applied to the programmable frequency divider 50 to generate a rectangle with a frequency corresponding to the data of the video signal. The rectangular wave signal is converted into a sine wave signal by a rectangular wave/sine wave converter 51 and output. The sine wave signal of a predetermined frequency output from the data/frequency converter 7 is amplified by the amplifier 10 and then passed through the telephone line interface circuit 12 to the telephone line 20.
transmitted to. On the other hand, a sine wave signal received by the telephone line interface circuit 12 from the other party through the telephone line 20 is amplified by the reception amplifier 13, then detected at the zero point by the zero point detector 14, and output as a rectangular wave signal. , the frequency of the output signal of the zero point detector 14 is counted by a frequency counter 15 using an oscillation signal of an oscillator 16, and then converted into original digital data by a frequency/data converter 17.
The digital data is converted into an original video signal by a D/A converter 18 and displayed on a monitor 19.

[0007] To explain the process of converting digital data into frequency, as shown in FIG. carrier frequency to 2
000Hz, a band of 2000Hz + 128Hz is required to transmit 8-bit data,
The average transmission speed is 16,000 bps. In this way, converting the 8-bit data "00000000" into a frequency becomes 1872Hz, which is the data "1111111".
1" is 2127Hz. Also, the relationship between the frequency band and the number of bits is as shown in Figure 4, the f1 frequency is 2N
−1 Hz, where N is the number of bits. Therefore,
If you want to convert 10 bits of data into frequency, f1
requires 210-1=512Hz. That is, the frequency band becomes f0+512Hz, and the average transmission speed becomes f0×Nbps. Therefore, when the transmission center carrier frequency is 2 KHz and 10 bits of data are sent, the transmission speed is 20 Kbps. Furthermore, FIGS. 5(A) to (D
As shown in FIG.
The frequency counter 15 starts counting the oscillation signal of the oscillator 16 at the rising edge of the rectangular wave signal as shown in FIG. It becomes possible to count the frequency of the sine wave signal by stopping counting at the edge part, but at this time, the reception frequency becomes fR = 1 (T × N × 2), where T is the frequency counter 15 , where N is the number of counts. In this way, the frequency of the sine wave signal can be determined based on the count value of the frequency counter 15, and data corresponding to the frequency can be obtained as shown in FIG. 5(D).

[0008]

As explained above, in the video signal transmission device using a telephone line according to the present invention, the transmission speed is determined according to the number of bits of transmission data and the transmission center carrier frequency, and a large amount of information can be transmitted in a narrow band. This has the effect of shortening the transmission time and quickly displaying the screen.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a video signal transmission device according to the present invention.

FIG. 2 is a detailed block diagram of the data/frequency converter shown in FIG. 1;

FIG. 3 is a frequency relationship explanatory diagram according to data of the present invention.

FIG. 4 is a waveform diagram showing the relationship between frequency band and number of bits according to the present invention.

FIG. 5 is a waveform diagram for received data processing of the present invention.

FIG. 6 is a block diagram of a conventional video signal transmission device.

[Explanation of symbols]

1...Camera 2...Analog (A)/Digital (D) converter 3...Memory 4...Timing generator 5...Memory control section 6...Central processing unit (CPU) 7...Data/frequency converter 8...Prescaler 9, 16 ...Oscillator 10...Amplifier 11...Buffer 12...Telephone line interface circuit 13...Reception amplifier 14...Zero point detector 15...Frequency counter 17...Frequency/data converter 18...Digital (D)/analog (A) converter 19...Monitor 20...Telephone line 50...Programmable frequency divider 51...Square wave/sine wave converter

Claims (4)

[Claims] 1. Video signal processing in which a video signal output by a camera (1) is converted into a digital signal, stored in a memory (3) under the control of a central processing unit (6), and then the stored digital data is read and output. means, video signal transmission means for converting the digital data outputted by the video signal processing means into a sine wave signal of a frequency corresponding to the digital data and transmitting it through the telephone line interface circuit (12); and the telephone line interface circuit (12). 12), which counts the frequency of the sine wave signal received through the telephone line, converts the counted value into the original video signal, and displays it on the monitor (19). Video signal transmission equipment. 2. The video signal transmission means includes an oscillator (9) that generates an oscillation signal of a predetermined frequency;
a prescaler (8) that frequency-divides the oscillation signal of the prescaler (8), a data/frequency converter (7) that converts digital data into a frequency corresponding to the digital data by the frequency division frequency of the prescaler (8), and the data/frequency converter 2. A video signal transmission device using a telephone line according to claim 1, further comprising an amplifier (10) for amplifying the output signal of the device (7) and applying the amplified signal to the telephone line interface circuit (12). 3. The data/frequency converter (7) comprises:
A programmable frequency divider (50) that converts digital data into a rectangular wave with a frequency corresponding to the frequency of the divided signal of the prescaler (8), and a programmable frequency divider (50) that converts the output signal of the programmable frequency divider (50) into a sine wave. A video signal transmission device using a telephone line according to claim 2, comprising a rectangular wave/sine wave converter (51). 4. The video signal receiving means includes a receiving amplifier (13) for amplifying a sine wave signal received through a telephone line interface circuit (12);
), a zero point detector (14) that detects the zero point of the output signal and outputs it as a rectangular wave signal, an oscillator (16) that generates an oscillation signal of a predetermined frequency, and the zero check using the oscillation signal of the oscillator (16). a frequency counter (15) for counting the output signal frequency of the output device (14); a frequency/data converter (17) for converting the output signal of the frequency counter (15) into original digital data; A video signal transmission device using a telephone line according to claim (1), comprising a digital/analog converter (18) that converts the output signal of the data converter (17) into an analog signal and displays it on a monitor (19). .